1. Field of the Invention
The present invention relates to a coil structure such as a coil sheath disposed in an endoscope or a coil sheath of a treatment instrument inserted through a treatment instrument channel of the endoscope and relates to the endoscope and the treatment instrument including the coil structure.
2. Description of the Related Art
Conventionally, in order to observe a part where it is difficult to observe an inside of a subject such as an interior of a body of an organism or a structure, an endoscope introducible into the subject has widely been used in, for example, a medical field or an industrial field.
For such an endoscope, for example, Japanese Patent Application Laid-Open Publication No. 5-115431 discloses a technique of a treatment instrument raising base for varying a direction of a treatment instrument or the like projected from a distal end portion of an insertion section. The treatment instrument raising base provided in a conventional endoscope is raised and lowered according to towing and relaxing of an operation wire provided in the insertion section.
Note that the operation wire is connected to an operation lever or the like provided in an operation section for remotely operating the treatment instrument raising base and is inserted into a densely wound coil pipe in the insertion section. The densely wound coil pipe is provided in order to suppress shrinkage of the insertion section due to the towing of the operation wire.